Apparatus for measuring the turbidity of liquids



. PriiZ S, 1931. v D. .1. MIDDENDORP 1,803,269

APPARATUS FOR MEASURING THE TURBIDITY OF LIQUIDS Filed Jan. 10, 1 29' 2 Sheeis-Sheet 1 ,Fz i- I I I F192; 6 n t I I JTVWF/n Jar D lNV N a April 28', 1931. D. J. MlDDENDO RP 1,303,259

APPARATUS FOR MEASURING THE TURBIDI'I'Y OF LIQUIDS Filed Jan. 10, 1. 29 2 Sheets-Sheet 2 Patented Apr. 28, 1931 airs!) STATES E DANIEL JOHANNES MIDDENDORLP, OF UTRECHT, NETHERLANDS, ASSIGNOR PATERSON, OF LONDON, ENGLAND TO WILLIAM APPARATUS FOR MEASURING THE TURBIDI'IY OF LIQUIDS liquid comprising a plurality of reflectors enclosing the liquid of which the turbidity s to be ineasured or indicated, means for opt1- rally projecting an image onto one of sand ---reiiectors and means for observing the numher of times said image is directed from one reflector to another through said liquid.

The invention also conslsts 1n apparatus for measuring or indlcatmg the turbldlty of --a liquid comprising a rectangular container for the liquid, nearly parallel mirrors upon opposite sides of said container and each mirror having a. transparent portlon arranged substantially on the same horizontal level but laterally displaced relatively to one 5 another, and a source of light adjacent to the transparent portlon 111 one of sald mirrors.

Further features of the inventlon Wlll be "apparent from the description given hereafter and from the appendant claims.

The accompanying drawings illustrate one convenient form of apparatus for carrying out the invention.

a T; Figure 1 is a longitudinal elevation partly "in section.

Figure 2 is a plan partly in section and Figure 3 is an outside elevation with a portion broken away.

Figure 4 is a diagram illustratlng the prinbipl-e upon which the apparatus operates.

In carrying my invention into elfect in one convenient manner I form my improved apparatus with a rectangular or other suitably shaped box, container, or caslng a formed from any suitable material or combination of materials, and opposite sides ofsuch container or receptacle I form as, or provide with, mirrors 6 0 which are preferably of silvered glass but whlch may be iormed from any other Suitable material.

Application filed January 10, 1929, Serial No. 331,426, and in Great Britain September 4,1923.

In one of the mirrors 5 I form a small transparent portion in the actual reflecting surface (as, for exampleby removing a portion'of the silverin'g from the silvered glass) which portion is in register with an aperture d in the outer metal or other Wall a of the tive image may thereby be formedalthough I it will be understood that any other form of image may be employed for optical projection through the liquid, and such image;

may be of circular, rectangular, or other suit able shape. A second transparent portion,

similar to that above referred to, is formed in the mirror 0 and is in register with an aperture (Z in the outer wall a, the transparent portion in-the mirror 0 being at approximately the same horizontal level as that in the mirror 6 but being laterally displaced relative thereto as clearly indicated in Figure 2.

The mirrors 6 and c are arranged at a slight inclination to one another and it will be evident to those skilled in optics that with such an arrangement of nearly parallel mirrors asuccession of virtual images will be formed by successive reflections between the two mirrors, which images will be located upon a circle struck from a centre at the point where the mirrors 6 and c (if produced) would meet and which will be spaced round the circumference of the circle at points separated by twice the areual distance between the mirrors 6 and 0. Thus an eye viewing the mirror I) through the aperture 03' will see a series of images in the mirror I), which images will be of progressively decreasing size. and intensity and will be separaed from one another by gradually decreasing distances, and While it is manifestly impossible in the scale adopted for the accompanying drawing to illustrate the locations of the respective images Figure 4 shows in diagram form the portions of the lines of sight joining the eye of the observer to some of the virtual images displayed in the mirror light is projected before passing through the b. It now there be inserted into the contransparent portion in the adjacent mirror.

tainer a a quantity of the liquid of which the In testimony whereof I have signed my turbidity is to be measured it will be clear name to this specification.

that the number of bright images visible to the eye of the observer Will give a measure or indication of the turbidity of the liquid since the greater the turbidity the greater Will be the amount of light absorbed in passing through the liquid and therefore the fewer will be the number ofimages visible 7 to the eye. Such turbidity may be indicated by reference to charts or tables or by means of a suitably calibrated scale Which may be provided in conjunction With the apparatus The invention is not to be limited to any particular size or shape of container nor to any particular optical means for producing a succession of reflections of an image through the liquid of which the turbidity is to be measured as such details may be varied in accordance with any particular practical requirements that may have to be ful- Having now described my invention, What I claim ashes and desire to secure by Le ters Patent, is v 1. Apparatus for measuring or indicating v the turbidity of a liquid comprising a conctainci' for the liquid, reflecting means having portions arranged in opposed relation to each other in the container, means to admit a beam of light into the container for projecting an image onto one of the reflecting portions, the

fireflecting means and the beam of light being so positioned in relation to each other that 'ing the number of times said image is directed from one reflectingportion to another adjacent to the transparent portion in one of the image is projected obliquely a plurality of times between opposed reflecting portions of the reflecting means, and means for observthrough said liquid;

2. Apparatus for measuring or indicating the turbidity of a liquid comprising a container for the liquid, reflectors on opposite sides of said container and slightly out of parallelism With one another, and a source of light adapted to form an image in oneof said reflectors and means for observing the num ber of times said image is directed from one reflector to another through said liquid.

3. Apparatus for measuring or indicating the turbidity of a liquid comprising a rectangular container for the liquid, nearly paralleL mirrors upon opposite sides of said container and each mirror having a transparent horizontal level but laterally displaced relatively to one another, and a source of light said mirrors.

i. Apparatus for measuring or indicating the turbidity of a liquidaccording toclaim 3 in which the source of light embodies a White opalescent screen through Which the DANilil. JOHANNES MIDDENDORP. 

